Rotary drive-transmitting coupling arrangements



March 19, 1957 J. A. PETRIE 2,785,550

ROTARY DRIVE-TRANSMITTING COUPLING ARRANGEMENTS Filed July 8, 1953 2 Sheets-Sheet 1 El; zazzflzfl 16 19a 2555202221254 March 19, 1957 J. A. PETRIE 2,785,550

ROTARY DRIVE-TRANSMITTING COUPLING ARRANGEMENTS Filed July 8, 1953 2 Sheets-Sheei 2 2.7851550 ROTARY DRIVE-TRANSMITTING COUPLING ARRANGEMENTS Taihes'AleXander Petrie,' l ittleover, DerbyyEn'glandy -as- ":signor .rto -"Rolls-Royce Limited, "Derby, England, a

Britishkompany Application :rul s, 1953, Serial No. 366,850

Gl'aims" priority; application Great Britain "July-25; 1952 15Clairns. on 64- 9 -'-[-hisinven tion .relatesto rotary drive-transmitting aeoupling arrangements. and is more particularly? concerned with :a rcbupling iof-iithe kind (hereinafter referred to ins -the kindzspecified);which is capable of transmitting a 'zdrive between-"the (coupled-spans whi1st-= accommodating wslight misalignment ofthe" rotational-axes 01:- the coupled fipa-rts andvwhich is" loaded in"tensionor conipression due to resultant aXial loads on the coupledr p arts. Such a coupling-is.suitable, forinstance, for diivingly intefc'on- -riectingvt-urbine ahd compressor-"shafts of-:a "gas-turbine engine, Candin such use the :coupling will usually be'in -rtensionsince the-resultant loads on the 'shaf'ts' due to the by; givingrthe sphericalsurfaces-a large diameterifi As a result: a coupling of the kind specified-has heretofore had ajlarge radial dimension.

- Thisfinventionhasfor an-object to. provide a coupling -of-the kindfspecified whereof t'heradial dimensionmay-be substantially reduced.

According-to the present invention,-a coupling. ofgthe {kindspecifiedcomprises a -ball-and-soekettype-connection: {and a :splined interconnection afforded by cooperating helica'lLspHnes of such hand-that, during torque:trans- 'irnissiong' axial -loads are causedvopposingtheloads applied by: the coupled par-ts on-the cooperating tspherical surfaces of the ballfand-soe'ket-type connection. -;By, adopting the arrangement of the present" inventionthe "effective load {of g-the cooperatingspherical surfaces -of---t'he-halland- -;socket connection may be-subs'tantialiy reduced-land thus the projescted area of :the cooperating spherical surfaces .andythe "over-all -ra-dialdimension of the couplingymay also -be reduced as compared with a corresponding coup-ling having straight axialsplines.

p Preferably itis arranged that the axial loading duet-o the helical splines is a finite amount greater thar'iyor less than the loadings' due tothe" coupledf parts so. that there fis" afinit-e loading of the cooperating spherical surfaces of "thehallland-socket interconnection the direction of action of which is known.

According to a preferred feature of this inventicnf one "of the cooperating spherical surfacesis formedon a third fiarthaving he-lical splihed portions; which third parflis "mounted .Unind w Perm 2 intoline with the splines on' -either of thecoupled pants, and locking'rneans is provided tolock. the third part with i-ts splined portions in' alignment with the splines on the jother of the" coupled parts,-which locking means is releasable to permit 'the splined portionsonthe thirdpartito be brought into'line with the splines on said one of the coupled parts.

In one arrangement according to this feature of the invention, the cooperating spherical surfaces-are provided -on the eridsof the helical sp'lined portions of the third part and on the=helicalls plines of the other of the Coupled parts. Ina second arrangementaccordingito thisfeature of the invention, the spherical: surfaces which, cooperate with those. on the third. part'yare formed "on: an: annular -me'rnber which-is separate from said other of the coupled parts, but 1secui'ed;;again st-movement'relative thereto.

The .third'part is-convenient=ly screw-threa d-ed to" the :Saidone OfqthSCOllPifldPfiftS.

' With this preferred"; arrangement, -;when the "helical rsplineson the coupled parts are being engaged ondis- 1 engaged, the wlockingmeansyis rendered inoperative and the-splines on the-third part are broughtinto-alignment -with=the-helical= splines on the said one 'of thecoupled -parts;but hemthecOuplingis engaged the helica l spline pontions onthe third pa-rt-arealigned jWlth: the helical splines on=-t=he other of the coupled parts and t-he locking ;rneans-isioper-ative-to:prevent-thc splines coming out of alignment. 7 p

,"Some embodiments of this invention will new be described which embodiments are illustrated respectively -in5theaccornpanying drawings finw hich,

Figural lS-3. Yil7/:- partlyin axial section through-a coupling in accordance with the invention,

Figure 2-;is a view corresponding to Figure l--of--a second" embodiment,

Figure 3 ise View correspondingato Figure l ofa third einbodiment, and

Figure4 isan illustration of the use of' the couplings.

Referring to Figure 1, thereis shown-an arrangement whioh isisuitable' fonusefwhen theload caused hy the he'lical splines is less than a-load tending to separate the coupled partsso thatthe resultantj load on the ball-and- "socket type connection is one" tending to separate the coupled parts.

Referring now'to' Figure 1fthefparts to befcou'pled are indicated as ashaft i0 whichniay, forfinstancefbe a cor'npre'ss orfshaft of ajgas-tiir'bine engine, and a'shaftfil which rnay,' forins'tance; he the shaft of a turbine'for "driving the compressor in this application there viv-ill be a load onthe shaft 10, due say to 'thecmnpressbr gpemmnaqmg in the direction of arrow '12 andfthere .will'be a lo a d; due say tothe turbine operation, acting on the turbine shaft 11 in the direction of arrow L125,

these'loads tending to separate the shafts.

The shaft "10 has formed internally of it atits Qendja set of helicalsplines 14 and the shaft 11 engages byits end within lthe end of the shaft 10 and isfo'rrned externall y with a set of helicalsplines 15 which cc-operate with the. splines 14. The hand of the. splines is, suchthat .vvhen the torque is-being transmittedfrom one shaftto theother,--;the directionof -rotation being indicated by arrow 36, a load isapplied to -the; shaft 10 as indicated bythe-arrowr-lfi' and a loadis applied to-theshaft 11 acting in the-"direction of arrow 17 so that therebyittie load tendingto separate theshafts lti-and' ll' is deereas ed. It is arranged; however";- that the loadsproducedtby the splines are'less than' those produced in the shaftsitl-and 11 due to the operation of, -say,the compressor-Lian "turbine;

tion which also allows slight misalignment of the two shafts 10 and 11.

The ball-and-socket type interconnection comprises a sleeve-like part 18 which is threaded on to the external surface of the shaft 10 at its splined end and the sleevelike part 18 is provided internally with a series of short splines 19 which are helical and of the same hand as the splines 14, 15 on the shafts 10 and 11. Preferably the thread by which the part 18 is connected to the shaft 10 is of square form with radial clearance so as to allow the splines 14, 15 to be concentric with the spherical face 19a despite manufacturing tolerances.

The surfaces 19a of the ends of the splines 19 which are nearer to the splines 14 are machined to be parts of a surface of a sphere having its centre on the axis of rotation of the shafts and having a diameter somewhat greater than the maximum diameter of the splines 19. Corresponding surfaces 15a are formed on the ends remote from the end of the shaft 11 of the parts of splines 15 adjacent the end of shaft 11, by cutting notches 15b in the splines 15 and these parts of splines 15 are made of a length somewhat greater than is necessary for cooperation with the splines 14 so that the spherical surfaced ends 15a are spaced away from the splines 14 when the shafts 10, 11 are coupled. The parts of splines 15 on the side of notches 15b remote from the end of shaft 11 are arranged to face the end faces of splines 19 when the coupling is engaged, in order to prevent telescoping f the shafts 10, 11 e. g. during assembly of the engine.

The sleeve-like part 18 has an axial extension 18a formed at its edge with a stepped notch afiording a pair of circumferentially spaced circumferentially facing shoulders 20 and 21 and engaged in the notch there is a tooth 22 formed externally of a sleeve 23 slidably mounted on the shaft 11. The sleeve 23 is splined to the shaft 11 through interengaging splines 33, 34 on the sleeve 23 and shaft 11, and is locked axially with respect to the shaft 11 by a spring-loaded press button 24 which engages an aperture 25 in the sleeve 23. With the press button 24 engaged in the aperture 25 the tooth 22 cooperates with the shoulder 20 in the extension 18a of the sleeve-like part 18 and holds the sleeve-like part in a position relative to the shafts and 11 such that the splines 19 are aligned with the splines and the spherical surfaces 19a, 15a are in abutment. These surfaces are loaded into engagement by the difference of the loads represented by the arrows 12 and 16, and 13 and 17.

When the button 24 is depressed against its spring, the sleeve 23 may be withdrawn axially so that the sleevelike part 18 may be rotated until the tooth 22 abuts against the shoulder 21 thus aligning the splines 19 with the splines 14 and allowing the shaft 10 to be withdrawn from engagement with the shaft 11.

Axial adjustment of shafts 10, 11 relative to one another may be effected by withdrawing shaft 11 until the splines 15 are disengaged from splines 14, but are still engaged with splines 19; rotation of shaft 11 relative to shaft 10 will then cause axial movement of member 18 due to its screw-threaded engagement with shaft 10.

Referring now to Figure 2, the arrangement is suitable for use when the load caused by the helical splines 14, 15 is greater than the loads tending to separate the coupled parts represented by arrows 12, 13 so that the resultant load on the ball-and-socket type connection is one tending to telescope the parts one upon the other or to draw them more closely together.

In this case the coupling again comprises a sleevelike part 18 threaded to shaft 10 and having splines 19 of helical form and of the same hand as the splines 14, 15 but in this case the discontinuous splines 15 having the notches 15b are formed as internal splines and the splines 14 on shaft 10 as external splines, and the spherical surfaces 19a of the splines 19 are at the ends of splines 19 remote from the shaft 10. The splines 19 have an axial length substantially equal to the axial length of the notches 15b, and as in the previous arrangement, the faces of splines 19 and of notches 15b which are not part-spherical will be aligned so that their abutment will prevent disengagement of shafts 10, 11 in the sense of separation, e. g. during assembly of the engine. The screwthread by which the part 18 is connected to shaft 10 is preferably, as in the construction of Figure 1, of square form with radial clearance.

As in the previous construction, when the splines 19 are aligned with the splines 15 the spherical surfaces 15a, 19a are loaded into abutment by the resultant load tending to telescope the shafts, and when the splines 19 are aligned with the splines 14 the shaft 10 may be disengaged from the shaft 11.

The sleeve-like part 18 is locked relative to the shafts 10 and 11 when in a position such that its splines 19 are aligned with the splines 15, by means of a tubular member 26 accommodated within the shaft 11. The tubular member 26 has at its end teeth 27 to engage with internal splines 28 which are formed on the member 18 and are of greater axial length than the teeth 27, and the tubular member also has teeth 29 formed externally of it in spaced axial relation to the teeth 27; the teeth 29 are engaged with internal teeth 30 on an annular member 31 clamped against the ends of the splines 15 by a threadedring 32.

To release the coupling, the tubular member 26 is withdrawn slightly axially of the shaft 11 to permit the teeth 29 to become disengaged from the teeth 30 but to allow the teeth 27 to remain in engagement with the splines 28. This permits the tubular member 26 to be used to rotate the sleeve-like part 18 on its thread with respect to the shaft 10 so as to bring the splines 19 into alignment with the splines 14, and thus to permit disengagement of the shafts.

The tubular member 26 may also be used to rotate the part 18 with respect to shaft 10 to effect relative axial adjustment of the two shafts 10, 11.

Referring now to Figure 3, there is illustrated a modified form of the arrangement shown in Figure 2. In this construction, instead of forming the co-operating part-spherical surfaces on the ends of parts of the splines 15 and 19, the part-spherical surface associated with the shaft 10 is formed on that end 18b of the sleeve-like -member 18 which is remote from the shaft 10 and is radially inward of splines 19, and the co-operating surface is in this case formed on the end 31a of an axial extension 31b of the member 31. The notches in the splines 15 to allow the splines 19 to come into line with them are conveniently square notches 150. The member 31 is held against rotation relative to the shaft 11 by teeth 35 which interengage with the splines 15.

Since in each of the constructions above described the axial load to be supported by the cooperating spherical surfaces 15a, 19a, or 18b, 31a is substantially reduced as compared with known arrangements, the maximum radial dimension of the coupling may be reduced.

The two coupling arrangements above described may be employed together in one machine. For instance, the arrangement illustrated in Figure 2 may be employed for coupling shafts which are nested within shafts coupled by the arrangement of Figure 1. Thus, for instance, as illustrated in Figure 4, the arrangement of Figure 1 may be employed to couple the rotors of a high-pressure compressor 40 and a coaxial high-pressure turbine 41,

and the arrangement of Figure 2 or of Figure 3 may be arranged to couple the rotors of a low-pressure compressor 42 and a coaxial low-pressure turbine 43, which are located coax-tally with the high-pressure compressor 40 and turbine 41 and respectively beyond the ends thereof so that the shafts 210 and 211 of the low-pressure compressor 42 and the low-pressure turbine 43 respectively extend through the shafts and 111 of the high-pressure compressor 40 and the high-pressure turbine 41. The sleeve-like member of the coupling beaxial load on said other shaft and abuts axially against said first axially-facing part-spherical surface to withstand the residual axial thrust between said coupled shafts.

15. A rotary drive tnansmitting coupling for transmitting a drive between two parts whilst accommodating slight misalignment of the rotational axes of the coupled parts, comprising first helical splines on the first of said parts, second helical splines on the second of said parts and interengaging with the first helical splines whereby on torque transmission an axial load is developed tending to displace said parts axially relative to one another, a third part, third helical splines on said third part, said third part being mounted on said first part for angular adjustment relative thereto about its axis between a first position in which said first and third helical splines are aligned and a second position in which they are out of alignment, a first axially-facing part-spher-ical surface on References Cited in the file of this patent UNITED STATES PATENTS 1,381,805 Drewdson June 14, 1921 1,770,744 Morgan July 15, 1930 2,172,662 Kuhns et al Sept 12, 1939 2,297,390 Burger Sept. 29, 1942 2,525,695 Lombard Oct. 10, 1950 2,691,875 Schmitter Oct. 19, 1954 

